This invention relates generally to microscope objectives and more specifically to objectives for clinical specular microscopes designed to view cornea endothelium cells used in diagnosing the health of the cornea.
Modern procedures for cataract extraction and replacement with donor corneal lenses have resulted in significant saving of human sight for many individuals. One of the problems associated with such lens substitution, and optometric diagnosis generally, however, is determining the health of the cornea. Studies have indicated that microscopic evaluation of the cornea endothelium is a means of measuring the trauma which the eye has undergone, and consequently the relative health of the cornea. This evaluation is based on the fact that endothelium cells, for the most part, are not regenerative and as a result calculation of the number of endothelium cells present indicates the presence or absence of trauma in the past.
In order to conduct such an evaluation, cornea endothelium microscopy has been developed. Heyer Schlute and Bio Optics, Inc., for example, have developed microscopes for use in viewing the endothelium. However, several difficulties have developed in the utilization of such microscopes.
One of the primary problems in the use of such microscopes is that the focal point of the lens, which is within the cornea, requires that the objective be extremely close to the exterior of the cornea. As a result, the objective frequently comes in contact with the cornea which prevents focusing of the microscope, causes some discomfort to the patient, and in some cases damages the objective lens. An additional problem has been that while it is relatively easy to count the number of endothelium cells present at a particular layer, it is extremely difficult to approximate the thickness of the endothelium layer, which is also an indication of the relative vitality of the cornea.
Accordingly, it is an objective of the present invention to provide an objective for cornea endothelium microscopes, and microscopes in general, which when coming in contact with the object being viewed, recede into the objective housing.
The use of spring biased objectives which allow such recession, generally, is old in the art and may be seen in the following issued U.S. patents:
______________________________________ Pat. No. Inventor Issue Date ______________________________________ 2,533,371 Heine Dec. 12, 1950 2,195,657 Ott Apr. 2, 1940 1,889,794 Sabel Dec. 6, 1932 1,557,503 Sabel Oct. 13, 1925 2,764,061 Kinder Sept. 25, 1956 197,096 Huel Apr. 10, 1958 ______________________________________ (Austrian)
However, none of the references cited discloses a spring loaded objective in which the ability to focus remains after the objective has come into contact with the object being viewed.
It is an additional objective of the invention to provide a microscope objective which allows the accurate measurement of the thickness of the material being viewed.